Furnace



June 13, 1939. H. c. wELLER 2,152,041

FURNACE Filed Aug. 18, 1937 2 Sheets-Sheet l mnentor f7.6. We ller v (Ittoneg H. C. WELLER June 13, 1939.

FURNAGE Filed lug. 18, 1937 2 Sheets-Sheet 2 www (ttorneg Peieuted' June 13, 1939 -uNiri-:D s'rAT-us PATENT loFl-lcu FURNACE e navey c.-we11er,.'ru1eae, ome, einer te surface mbustion Corporation, Toledo, Ohio, a

` y corpora ion of New York v Appueetieu August 18,. 1937, serial Nu. 159,747

`14 claims.A (Cl. zes-s) The present invention relates to tunnel type furnaces through which the `work is passed in a pathl which is U-shape in Aplan -and -tlie object of the invention is to provide for'the heating of the work by fuel fired radiant tubes arranged in a novel manner to the lend that the 'highest temperature may be at the return bend end of said path with gradually decreasing temperature" from that end to the work entering end of the 1o furnace. y In the drawings, wherein the preferred form ,of the invention is, disclosed,

, Fig. 1 is a vertical longitudinal sectional view of a furnace embodying the present invention; 1 6 the view being along line i-i onFig. 2;

Fig. 2 is an enlarged horizontal section of the furnace portion omitted;- Fig. 3 is a vertical sectional view taken sub-y stan'tiallyon line 3 3 of Fig. 2;

Fig. 4. is a sectional detail view of a burner; Fig. 5 is a sectional'detail view of an eductor; Fig. 6 is a vertical longitudinalsectional'view of a furnace embodying a modified form of the Figs. 7, 8 and 9 are, respectively, vergcal cross sections along lines 1 1, 8 8 and 9 9 of Fig. 6, and

Fig. 10 is a horizontal sectional view offa furnace embodying another form of the-invention.

Referring' to Fig. l, the furnace illustrated is of y,the `type having a heating zone i0 at an ele.

vatedlend of a relatively long tunnel through which the work ispassed in a path which is U- shaped in p lan', the return bend of said path be- .4 5 through the ltunnellfls a second set Aof iloor tubes uf il, these tubes extending` throughthe otherv lateral half of the heating zone i0 and' then e'xf tending over into the same lateral half of 'the tunnel as the other tubes, as indicated' at ila, lit being noted that except in the heatingzone there ,are no tubes in that lateral half of 'the tunnel through which the outgoing work passes.'- Y For conveniencefof description', that side por- 'Q- tion of theftunnelbetween the heating 'zone-IB 56 and the work intake end of the tunnel will shown in Fig. l with an intermediate' i6. rlThe exhaust end of all of said tubes is at 10, the opposite end of said tunnel as indicated at il.

The heating zone iii is centrally divided by a vertical partition wall,i8. Disposed along this wall at each side thereof is a heating tube i9 of hairpinv type' whose fuel intake end i9'` extends 15 through the oor of the tunnel and whose exhaust end Ilia extendsl through the roof of the same. Also disposed in the heating zone along the. side wall of the tunnel is a'hairpin type tube '20 whose intake and exhaust endsboth extend 20 through the end wall il of the tunnel. By thus .providing the heating zone i0 with a plurality of heating tubes, heat is uniformly applied to the. work as it passes therethrough.4

Each of various heating tubes described isin. 25 dependently red, 'the firing system being the same for each tube. At the f uel intake end of -ach tube is a burner indicated by thefletter A,

o f the type shown in Fig.'4 and at the exhaust end of each-tube is an eductor indicated by the 30 letter B, of the 4type shown in Fig. 5. For pur- Aas extending a substantial. distance into the inlet end of the heating tube T to compensate for the vthickness of the furnace wall i6. 'I'he fuel tube 2i is of comparatively large diameter with- 40 out any constriction at its discharge end such vas would interfere with the projection of a fuel is provided with a plurality of^small passages 50 through which thel mixture supplied to tube 24 OWS. y l'rne fuel tube 2| extends beyond the tube u 'jandI the spacebetween the twowtubes at the discharge end of thering 2l forms an annular com- 5 issuing from the inner tube 2|.

bustion chamber .2 8 for the mixture ilowing through the ring. The outer ends of the tubes V2| and 24 become highlyheated and along with the high temperature gases issuing fromsaid chamber 2l constantly insure ignition of the fuel Air to support combustion of the fuel issuing froni tube2 Iv isffinduced to enter the heating tube T at ,its fuel intake end by the eductor shown in harge end of th e Fig. and located at the. heating tube. Said eductor comprises a jet oriilce nozzle 29 positioned to, discharge into an eductor tube 30 forming 'in eifect an extension of the heating tube. A uifLPressure supply pipe 3i is .provided with a regulating valve 32 l'to permit the entraining eil'ect to. be adjusted-as desired. As the strong induced draft -throughrthe heating tube tends toipull the iiame away from the fuelv \tube 2|, thus causing it to be extinguished,`the previously described combustion chamber 28 con- 'stantly insures ignition of the fuel and air where theyintermix in combustible proportions.

'I'iie type of radiant tube heating element T above described provides the means for heating the heating zone III inthe desired manner due tothe fact that the fuel is caused tu burn within the tuberor a substantial portion of 'its length.

As the entraini'ng eilect of the 'eductor tends to draw the iiame andthusl the he'at toward the outlet end of the radiant tube it is to be noted that the'heatisradiatedin agraduallydiminishring degree toward the outlet endf the Thus, high heat concentration takes placein the zone Il which is in eect 'a heat pocket undisturbed by'gas'or'air currents due to its elevated position, while the remainder of the tunnel serves fas a heat exchange zonewherein heat is radiated from the outgoing. hot articles to the incoming com articles and wnereinneat iardiased from the tubes ila'that'cross over to the preheating portion of the tunnel 'to preheat the incoming;

articles. The cooler portionsof the radiant tubes also radiate -sumcient heat to eifect preheating of the incoming articles.

Byfavoiding the use of the radiant tubes in th outgoing portion of the tunnel, the cooling portion of the tunnel permits radiation to take place from the outgoing articles, thus enabling the articles to be gradually cooled as they approach the discharge end of the timnel structure. To

y further insure a high concentration of tempera' tureintheheatingzoneilthehairpintype radiant tubes" .and 2lare used.

In' operation, it wm be understood 'maewnen the furnace is usedasan enameling furnace, the articles are suitablyena'meled or coated asfby dipping, spraying or otherwise and si'xbsequentlyl fed intoth tunnel 'from.the rightas viewed in Fig. l. Asthe articl pass into one side of the heating zone and arcuately around the partition Il and throughthe other side of the zonk they are highly heated to the desired temperature to take the enamel coating. Passing from the heat- Ving zone, the articles radiate heat to the incoming articles. As the cooling zone is free of heating means, the articles'radiate their heat and are cooled comparatively quickly as they approach thev discharge end of the tunnel, from which the articlesare v.carried into the outside 7atmosphere tofurther'cool.

l modined form of the invention shown in' Pigs.69, theheatingzon'e is indicated-at il' and the central `vertical-partition wall at il'. In each portion of. the. heating zone il' are ar' ranged two 'side wall tubes and a iloor tube.' Theside wall tubesin the incoming portion or" the tunnelareindicated at l0 and 42 and theiloor tube at V4I and the side wall .tubes intheoutgoing portion at I3 and: and the oor tube at M. Each of these .tubes in the heating zone is The ming end of each tube is .provided with a burner A of the type shownin Fig. 4 and the n exhaust end' of eachtube is provided with an Aeductor B oi thetyp'e shown in Fig. 5. All of the tubes as they leavethe heating zon extend for a portion of their length adjacent the door of the tunnel below th'e path'of the incoming work; and those in the work-outgoing -side voi' the heating zone cross -over to the opposite side -of ,the tunnel and are positioned therealong adjacent one side .of the path of the incoming work. Thus, ythe incomingwork receives heat from the 'tubes on the wallv and the outgoing -work respectively. As the incoming work is carried toward the heating zone the temperature is graduf -ally increased'toreach a maximum in the heating zone where' the work'is substantially surrounded by heating elements; In Figs. v6, vi! and 9, those,` numerals having the sunix a" indicate the posif- 4I in the preheating.`

tion of the tubes I3, M and zone ofthe tunnel.A y

In the modiiiedform of the inventionshown'in Fig. I l,` the-heating zone Il is of sarcuate shape and comprises an ofuter arcuate wall il and an interior centrally located partition o r pillar 52 having anarcuate portion denning the incoming and outgoing portions of the heating chamber.

- .The radius of -curvature oi'j the arcuate4 portion of the heating zone is substantially greater than halfthe width of the straight portionof the tunnel to provide an enlarged circular portion for the return bend end-of the U-shape path of the -A set of tubular heating'elements Il 'of substantially hook-shapeare arranged adjacent the iloor of the heating zone l., and have-their 'inlet ends Il projecting through thegwall li. acent .55

the discharge end of the heating zone an prol vided with burners A of'the type shown in From the heating zone the heating Atubes -extend 'along 'iioor ofthe preheatingwzone ofwthe timnel and at.their discharge ends are provided witn'euuetors B uf the type shown m mg. 5. n.

additional heating tubes may be arranged' adjacent the wall il, as well as along the oor,A to provideaddition'al heat in the heating zone.` The shape of the tubes 5l lendthemselvesto comparatively rapid and intense heatv radiation as the curvature thereof causes the intermixing of air 'and' gas 'soon after entering the tubes, and high temperatures may thus be produced infthe zone. Y

lWhistliclainis: .I 1. -In a furnace, the combination of a recuperative chamber and a heating chamber forming atunnel, means for moving work into and out of the timnel-in a Ll-shaped path, the return bend of path lieing inthe heating chamber and,

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gases to iiow through said tube in direction opposite to that of the incoming work.

2; In a furnace, the combination of arecuperative chamber and a heating chamber forming a tunnel, means for moving work into and out of'l the tunnel in a U-shape path, the return bend of said path being in the heating chamber and the legs of said path extending through the re-.

cuperative chamber, means for producing a rising temperature gradient in the tunnel indirection toward the heatingchamber, said last named means comprising a heating tube having a substantial 'portion of its length within the heating chamber and which extends into the recuperative chamber along the work-incoming side thereof,

and a burner firing into that end of the tube nearest the heating chamber.

'3. In aV furnace, the combination of a recuperative chamber and a heating chamber forming a tunnel, means for moving work into and out of the tunnel in a U-shape path, the return bend of said path being in theheating chamber and the legs of said path extending through the re.- cuperative chamber;v means for producing a rising temperature gradient in the tunnel in direction toward the heating chamber, said last named means comprising a heating tube which extends for a portion of its length along the work-incoming side of the recuperative chamber and then passes through the heating chamber and out of the latter chamber'adiacent thework-outgoing side thereof, and a burner firing into that end f the tube which extends out of the heating chamber.

4. In a furnace-the combination of a recuper` l ative chamber and a heating chamber forming a tunnel, means for moving work into and cut of the tunnel in a U-shape path, vthe return bend of..

said path being in the heating chamber and the legs of said path extending through the recuperative lchamber, means for producing a. rising temperature gradient in the tunnel in direction means comprising a hook-shape heating tube, the longer leg of said tube extending along the workincoming side of the recuperative chamber, the hook portion of said tube being in the heating chamber, anda burner firing into thehook end of the tube.

5. In a furnace, the combination of a recuperative chamber and a heating chamber forming a tunnel, means for moving work into and out of the tunnel in a U-shape path, vthe return "bend of said path being in the heating chamber and the legs of said path extending through therecuperative chamber, means -for producing a rising temperature gradientin-the tunnel indirection toward the heating chamber, said last named means comprising a hook-shape vheating tube,l the longer Ileg of said tube` extending along the work-incoming side of the recuperative chamber, the hook portion of saidtube being substantially coincident with the'return bend of said U-shape path, and a burner firing into the hook end` of the-tube.

' 6. In a furnace, the combination of a recuperative chamber and a heating chamber forming a tunnel, means for moving work into and out oi.'

the tunnel in a U-shape path, the return bend of said path being in the heating, chamber and the legs of said path extending through the recuperative chamber, means for producing a rising tem-' perature gradient in the tunnel in direction to-v ward the heatingv chamber, said last named meanscomprising a heating tube which extends for a portion of its length along the work-incoming side of the recuperative chamber and then passes *laterally across the latter chamber and into the heating chamber, and a burner firing into that end of the tube nearest the heating chamber.

7. In a furnace, the combination of a recupere ative chamber and aI heating chamber forming'a tunnel, means for `moving work into and out of lthe tunnel in a U-shape path, the return bend of -said path being in the heating chamber and the legs of said path extending through the recuperi ative chamber, means for producing a rising temperature gradient inthe tunnel in direction toward the heating chamber,said last named'ineans comprising a heating tube which extends for a portion of its length along the sidewall of theI recuperative chamber nearest the incoming, work and then passes along the oor of the recuperf ative chamber below the incoming work and then passes laterally across the latter chamber and into that end chamber.

.8. In a f ace, the combination of walled structure l'forming a tunnel which is closedat one of the tube nearest the -heating end and open at its other end, a heating tube 'dis-y posed adjacent one side wall of the tunnel,` a second heating tube having an end portion d i'sposed adjacent the other side wall and a portion l extending laterally toward said first heating tube,

and means for supplying heating gases to one end of each of said tubes. 9. In a furnace,fthe combination of a walled structure forming 'a tunnel which is closed at gasesto one end of ea'ch of said tubes. toward the heating chamber, said last named 10. In a' furnace, the combination of a walled structure forming a tunnel which is closed at one end andoperr at its other end,a heating tube dis posed adjacent one side wall of the tunnel, and a -second heating tube having end portions disposed tubes having U-shape portions disposed adjacent the closed end of .said tunnel.

"into the heating chamber, and a burner nring 11. In a furnace,` the combination of a walled structure forming a tunnel which is closed at-one end and open at its other end, a set of heating tubes disposed adjacent one side of the tun-'- nel, a second set of heating tubes having end portions disposed adjacent the other side of the tunnel and portions extending laterally toward said first set of tubes, and a. plurality of heating tubes of U-shape configuration disposed adjacent the closed en d of the tunnel and between said first .and second sets'of tubes.

.12. In a furnace, the combination of a struc` 'ro I ture forming a tunnel having a heating zone at one end and open at its other end for the ingress YI l 'floor o! the tunnel, a burner ringrinto one and egress of. work, means for moving the work through ythe tunnel in a Ufshape path `ot which the return bend is in said heating zone,

for producing heat` in said zone comprising la U-shape tube between the legs of and inwardly A of the return bend ot'said path and'whose ends extend out of said lione through the roof and end of said tube.

13. In a furnace, the combination of a.struc ture forming a tunnel which is closed at one end and openat its other end for the ingress and egress of work, a coneyor for conveying the work into and out of the tunnel .along av U-sbape path ot which the return bend is at the closed end oi the tunnel, alpartition .spaced from the closed end of said tunnel and around the end otwhich the work is passed, `it heating tubevdisposcdonl which the 'return bend is at the closed end of the and open at its other end for the v'ingress and egress or work, means for moving the work into and out ofthe tunnel along a lU-shape path of tunnel, a heating tube disposed along one,side of A the tunnel and in heating proidmity to the in# coming work, and a heating tube coextensive with said m'st tube throughout a major portion of its length and diverging into heating proximity to the outgoing work adjacent the closed end vof the tunnel.Vv 

